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[Qemu-devel] [PATCH] linux-user: In fork_end(), remove correct CPUs from

From: Peter Maydell
Subject: [Qemu-devel] [PATCH] linux-user: In fork_end(), remove correct CPUs from CPU list
Date: Tue, 7 Jun 2016 17:31:04 +0100

In fork_end(), we must fix the list of current CPUs to match the fact
that the child of the fork has only one thread. Unfortunately we were
removing the wrong CPUs from the list, which meant that if the child
subsequently did an exclusive operation it would deadlock in
start_exclusive() waiting for a sibling CPU which didn't exist.

In particular this could cause hangs doing git submodule init
operations, as reported in https://bugs.launchpad.net/qemu/+bug/955379
comment #47.

Signed-off-by: Peter Maydell <address@hidden>
 linux-user/main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/linux-user/main.c b/linux-user/main.c
index b6da0ba..150a356 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -130,7 +130,7 @@ void fork_end(int child)
            Discard information about the parent threads.  */
         CPU_FOREACH_SAFE(cpu, next_cpu) {
             if (cpu != thread_cpu) {
-                QTAILQ_REMOVE(&cpus, thread_cpu, node);
+                QTAILQ_REMOVE(&cpus, cpu, node);
         pending_cpus = 0;

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